This invention relates to lasers and more particularly to an optically pumped laser with a rod-type lasing medium supported on a heat sink.
The patent application identified above describes an optically pumped laser in which the lasing medium is a cylindrical rod supported on the end of a heat sink within an elliptical cavity which focuses the pump light into the rod. In order to enhance the performance of the laser, it is desirable that the area of contact of the laser rod surface by the heat sink be as large as possible for cooling the rod. At the same time, it is also desirable to expose a large rod surface area to radiation from the pump lamp to obtain maximum pumping efficiency. A trade-off between these two design objectives in the assembly described in the above-identified application resulted in a width of contact between the heat sink and the laser rod of 120.degree..
A disadvantage of this 120.degree. rod surface contact is the resultant distortion of the laser beam phase wavefront caused by thermal lensing effects exhibited by the rod. As a consequence, the beam wavefront profile is shaped so that it cannot be properly focused by conventionally shaped laser cavity mirrors.
This invention is directed to a uniquely simple solution to this problem.